Fix pg CommonJS/ESM interop

server/db.ts

@@ -1,7 +1,9 @@
-import { Pool } from "pg";
+import pg from "pg";
 import { drizzle } from "drizzle-orm/node-postgres";
 import * as schema from "@shared/schema";
 
+const { Pool } = pg;
+
 if (!process.env.DATABASE_URL) {
   throw new Error("DATABASE_URL must be set.");
 }